Topic 1 - classification

?

Hierarchical classification system

  • 7 levels of taxonomic structure which are based on characteristics (morphology, embryology, biochemical analysis (protien analysis, DNA analysis)):
    • Kingdom - Animalia, Plantae, Fungi, Protoctista, prokaryote.
    • phylum - a large grouping of all the classes that share some common features.
    • class - a grouping of similar orders.
    • order - a grouping of related families.
    • family - a grouping of similar genera.
    • genus - a group of species that are very closely related. 
    • species- a group of organisms that can successfully interbreed to produce a fertile offspring.
1 of 10

The five kingdoms - Prokaryotae

  • Bacteria have prokaryotic cells.
  • The cells have no distinct nucleus. 
  • Don't have membrane-bound organelles
2 of 10

The five kingdoms - Protoctista

  • A collection of eukaryotic organisms including algae - photosynthetic but not plants.
  • The Protoctista seems to be the group in which organisms end up if they are not fungi, plants or animals.
  • Many have eukaryotic cell features such as chloroplasts. 
3 of 10

The five kingdoms - Fungi

  • Fungi are not able to photosynthesize.
  • Their cell walls are made of a polysaccharide called chitin.
  • Their bodies are composed of masses of filaments called hyphae which are not divided up into separate cells.
  • most are saprobiont, obtaining their food by the extracellular digestion of dead organic material.
  • Fungi have membrane-bound organelles.
4 of 10

The five kingdoms - Plants

  • Plants are multicellular.
  • They have chlorophyll and are photosynthetic.
  • Their cells have a cellulose cell wall and sap-filled vacuole.
  • Many have proper stems, roots and leaves.
  • Primitive plants reproduce by spores; more advanced forms, such a flowering plants, produce seeds.
5 of 10

The five kingdoms - Animals

  • Animals are multicellular.
  • They are heterotrophic - they are unable to make their own food and need a supply of organic food material.
  • They have nervous systems and are able to move about.
  • Growth occurs throughout the body.
6 of 10

Phylogenetic classification system

  • Based on evolutionary history.
    • all species evolve from one common ancestor.
  • LUCA - last universal common ancestor.
  • Analogous structures: different structures but same function - arise due to convergent evolution.
  • Homologous structures: same structures different functions - an example of adaptive radiation.
  • Pentadactyl limb:
    • an example of a homologous structure.
    • five fingered/toed limb.
    • shared with mammals, reptiles, amphibians, and birds but not fish.
  • All organisms have DNA with 1 of 4 bases  - this is the main piece of evidence for LUCA because he has all 4.
7 of 10

Three domain classification system

  • This is a way of classifying organisms based on differences in ribosomal RNA structure.
  • Classified into 3 domains and 6 kingdoms.
  • Domains:
    • archaea
    • bacteria
    • eukarya
  • Kingdoms:
    • Archaebacteria
    • Eubacteria
    • Protista
    • Fungi
    • Plantae
    • Animalia 
8 of 10

Natural selection

  • Overproduction in offspring but no increase in population - shows a struggle to survive.
  • Variations occur in offspring.
  • Due to competition and struggle to survive only the offsprings with beneficial variations in characteristics survive.
  • The offsprings that survive can go on to reproduce and pass on their beneficial characteristics to future generations of the species.
  • Over time the number of individuals with the beneficial characteristic increases.
9 of 10

Mass extinction

  • Extinction: permanent loss of a species.
  • Mass extinction event: an event that causes the majority of species to go extinct.
  • Evolutionary bottleneck: the small amount of species that survive a mass extinction event.
10 of 10

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all classification resources »